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A high‐performance polycarbonate electrophoresis microchip with integrated three‐electrode system for end‐channel amperometric detection
Author(s) -
Wang Yurong,
Chen Hengwu,
He Qiaohong,
Soper Steven A.
Publication year - 2008
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/elps.200700377
Subject(s) - amperometry , polycarbonate , electrode , electrophoresis , chromatography , channel (broadcasting) , analytical chemistry (journal) , chemistry , materials science , computer science , electrochemistry , telecommunications , organic chemistry
Abstract A fully integrated polycarbonate (PC) microchip for CE with end‐channel electrochemical detection operated in an amperometric mode (CE‐ED) has been developed. The on‐chip integrated three‐electrode system consisted of a gold working electrode, an Ag/AgCl reference electrode and a platinum counter electrode, which was fabricated by photo‐directed electroless plating combined with electroplating. The working electrode was positioned against the separation channel exit to reduce post‐channel band broadening. The electrophoresis high‐voltage (HV) interference with the amperometric detection was assessed with respect to detection noise and potential shifts at various working‐to‐reference electrode spacing. It was observed that the electrophoresis HV interference caused by positioning the working electrode against the channel exit could be diminished by using an on‐chip integrated reference electrode that was positioned in close proximity (100 μm) to the working electrode. The CE‐ED microchip was demonstrated for the separation of model analytes, including dopamine (DA) and catechol (CA). Detection limits of 132 and 164 nM were achieved for DA and CA, respectively, and a theoretical plate number of 2.5×10 4 /m was obtained for DA. Relative standard deviations in peak heights observed for five runs of a standard solution containing the two analytes (0.1 mM for each) were 1.2 and 3.1% for DA and CA, respectively. The chip could be continuously used for more than 8 h without significant deterioration in analytical performance.